Cause analysis and control technology of paperboar

Second, the lack of understanding of the law of moisture change during the period from tile line to machine printing is an important reason for the line burst. When the paperboard comes out of the tile line, although its overall moisture content is relatively high, the moisture content of each layer of paper is extremely unbalanced. The test shows that in the dry season, when the paperboard is just produced from the paperboard line, the moisture content of the face paper is about 8%, and some are even lower than 6%. When the paperboard is stacked for 4 hours, the moisture of each layer of paper tends to balance, and the moisture of the face paper increases to more than 9%. Therefore, if the paperboard is printed on the machine when it just comes out of the tile line, it is easy to cause the line pressing position to burst due to the low moisture content of the face paper at this time. Therefore, the cardboard should be stacked for enough time after production, and then printed on the machine after the moisture of each layer of paper reaches balance. When the moisture of the paper board surface and inner paper is low, the printing line pressing will be carried out, and the line pressing part will produce micro cracks. After that, even if the moisture of the surface and inner paper increases, the line burst problem can not be avoided

if the delivery time of the customer is too short to have sufficient time to balance the moisture of the paperboard, warm water on the surface of the paperboard is the most direct and effective way. Wet water is best to avoid affecting the printing parts, otherwise it will have an adverse impact on the printing industry to further improve its market share in the industry. If conditions permit, a wet plate can be made by using the waste field plate. First wet the line pressing part with a printing station, and then print. In this way, the line pressing position can be wet quickly without affecting the printing quality

when the bursting of paperboard cannot be improved by controlling the moisture content, the use of kraft linerboard with better folding resistance can also effectively reduce the bursting degree of carton. At present, there is no reliable test to show that it can completely avoid the wire burst problem. According to the test data, the Kraft linerboard with 100% wood pulp as the surface paper and lining paper will also burst when its moisture content is as low as 6%. Generally, the folding performance of base paper can be reflected to a certain extent from the two physical properties of longitudinal tear and burst resistance. The folding performance of base paper with high longitudinal tear and burst resistance is also correspondingly higher

when configuring paper, unless there are special requirements, we should try to reduce the difference in gram weight of paper in the surface. For example, we should try to avoid the production of k = B and K = C paperboard, because it is easy to lead to bursting of B paper or C paper if there is residual chlorine and some oxidizing fungicides in the water. In fact, the vast majority of corrugated board processing manufacturers do not produce k = B, k = C corrugated board, which shows that this principle has long been recognized and followed by peers. If this configuration has to be adopted for objective reasons, the best way is to choose long fiber kraft linerboard for the layer with low gram weight

for corrugated board with different strength, we should treat the selection of opposite and inner paper differently. For the edge compression strength of paperboard or the compression strength of the whole carton, Yu Wei pointed out that the carton with higher strength requirements should also be matched with the paper with higher folding resistance

for a, Ba, BCA and other corrugated boards with a pit combination, selectively use base paper with good folding resistance to fit with a corrugated board, which can also effectively prevent the cardboard from bursting

when slotting and pressing the paperboard, pay attention to adjust the position of the concave convex rollers on the upper and lower parts of the pressing line, and timely adjust the slight deviation in the slotting and pressing process. Moderately reducing the pressure of the line can also improve the line burst, but this method may cause poor forming of the carton

if conditions permit, the printing pressure can be increased, the dry and hard paperboard can be softened appropriately, and the wire burst can also be reduced. However, this method will greatly reduce the compressive strength of cartons, so it can not be abused

(Guan Guoping)